1. Field of the Invention
The present invention relates to a plurality of connected optional apparatuses, such as external sheet feeding apparatuses or external sheet discharging apparatuses, that are connected to an image forming apparatus, and to an image forming apparatus, such as a copier, a facsimile apparatus, and a printer, that can be connected to the optional apparatuses.
2. Description of the Related Art
An image forming apparatus is often configured to increase a sheet feeding capacity and a discharged-sheet mounting capacity by including a plurality of external sheet feeding apparatuses, such as optional feeders, or external sheet discharging apparatuses, such as optional trays, connected to the image forming apparatus. Such external apparatuses (hereinafter termed “optional apparatuses”) are generally disposed below or above an image forming apparatus. In many cases, optional apparatuses can be stacked in several stages.
In an image forming apparatus connecting to these optional apparatuses, discrimination among the optional apparatuses is generally performed by providing each of the optional apparatuses with an identifier, such as a sheet-feeding-port number in an external sheet feeding apparatus, or a discharged-sheet-tray number in an external sheet discharging apparatus. That is, each optional apparatus is discriminated by being provided with an identifier, such as a numeral, a letter, or the like.
Conventionally, when there is an identifier for each optional apparatus when a plurality of optional apparatuses are used in a stacked state, for example, the process of attaching a label on which a corresponding identifier is printed is performed after installing an optional apparatus, and as a result the operation of installing optional apparatuses becomes complicated.
In order to solve such a problem, Japanese Patent Application Laid-Open (Kokai) No. 11-246059 (1999) discloses a configuration for allowing automatic switching of an identifier for a connected optional apparatus.
This conventional configuration will be described illustrating optional feeders, serving as external sheet feeding apparatuses. As shown in FIG. 8, a sliding member 4 having an projection 9 protruding upward is provided so as to be vertically slidable in each optional feeder 2. The sliding member 4 is urged upward by a coil spring 7. Two identifiers “2” and “3” are integrally formed on the sliding member 4 at constant intervals in a sliding direction. When optional feeder 2 is in one stage, the identifier “2” disposed downward from among the two identifiers is displayed from a display window 8 provided in the surface of a protective housing of the optional feeder 2. A hole 11 in image forming apparatus 1 is provided at a position facing the projection 9 of the sliding member 4 of the uppermost optional feeder 2. When connecting the uppermost optional feeder 2 to the lower surface of an image forming apparatus 1, the projection 9 is inserted into the hole 11. Since the sliding member 4 does not move, the identifier of the optional feeder 2 is a sheet-feeding-unit number “2” provided at the lower portion of the sliding member 4.
Since the base of the optional feeder 2 is flat, when an optional feeder 2 of the second stage is connected below the uppermost or first optional feeder 2, the projection 9 of the lower optional feeder 2 contacts the base of the uppermost optional feeder 2 to push the sliding member 4 downward against the spring force of the coil spring 7. As a result, the identifier “3” provided at the upper portion of the sliding member 4 is displayed thru display window 8 provided on the surface of the protective housing, to set the sheet-feeding-unit number of the lower optional feeder 2 to “3”.
In the above-described conventional configuration, however, since switching of the identifier is performed using the optional apparatus disposed adjacent to the first optional apparatus and switching can be performed only between two types of identifiers, it is impossible to deal with a configuration allowing stacking of at least three external sheet feeding apparatuses.